Stoker



Dec. 12, 1933.

H. E PREsTN STOKER Filed June 16 1930 6 Sheets-Sheet l Dec. 12, 1933.

Filed June 16, 1950 6 Sheets-Sheet 2 ,gluefaaom Dec. l2, 1933. H. E. PRESTON STOKER Filed June 16, 1930 6 Sheets-Sheet 3 nu af 6 Sheets-Sheet 4 v H. E. PRESTON STOKER Filed June le, 1930 Dec. l2, 1933.

Dec. 12, 1933. H E, PRESTON STOKER Filed June 16, 1930 6 Sheets-Sheet 5 H. E. PRESTON STOKER Filed June 15 1930 6 Sheets-Sheet 6 1 j l C rlfi fill: il 1| r ll| Il lVLT Illu IL rl. v n

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Dec. l2, 1933.

Patented Dec. 12, 1933 s'roKEn' Herbert E. Preston, Philadelphia, Pa., assigner to American Engineering Company, Ihilarlel phia, Pa., a corporation of Pennsylvania Application June 16, 1930. Serial No. 461,528

l Claims.

This invention relates to improvements in stokers, and more particularly to improvements in stokers of the type disclosed in my copending applications Serial Numbers 263,900, and 425,316.

`One of the objects of the present invention is to provide a stoker of the stated type having novel and improved means for controlling expansion resulting from the high temperatures to which the structure is exposed.

1,0 To this general end, another object of the invention is to provide a stoker comprising alternately arranged retort and tuyre sections in which provision is made for permitting expansion in each individual retort section without effect upon the adjacent retorts, whereby accumulative expansion in the stoker structure as a. whole is avoided.

To this same end, the invention contemplates the provision of a stoker structure in which pro- 80 vision is made for absorbing transverse expanf sion in each of the retort sections in the adjacent tuyre section or sections, whereby .excessive expansion in the structure as a whole is avoided.

86 A still further object of the invention is to Vprovide a Stoker structure in which provision is made for self adjustment of the parts due to longitudinal expansion.

A further object of the invention is to provide a stoker structure of theA general type disclosed in my aforesaid copending applications having novel means for reinforcing and strengthening Athe structure, as hereinafter set forth.

.Still another object of the invention is to proi5` vide for a Stoker of the statedcharacter a novel and improved retort construction in which sift- Y ings are reduced .to a minimum. To this end also, the invention resides in part in the provision of novel means for excluding siftings from between the side walls of the retort and the reciprocatory pusher elements.

Still another object of the invention is to provide a stoker having a novel and improved retort construction tending to avoid undue dis'- Vturbance of the fuel-bed, thereby to maintain a more solid and compact bed than heretofore has been possible.

The invention further resides in certain novel and improving structural ,details and features hereinafter set forth and illustrated in the attached drawings, in which:

Figure 1 is a vertical` sectional view of a portion of aV stoker made in accordance with my invention;

Fig. 2 is a vertical section on the line 2 2', Fig. l;

Fig. 3 is a more or less diagrammatic elevational view, partly in section, illustrating details of the stoker structure; f

Figs. 4 and 5 are plan views of elements of the structure;

Fig. 6 is a section on the line 6--6, Fig. 4;

Figs. 'l and 8 are sectional views on lines 7-.7 and 8 8, respectively, o f Fig. 4; 65

Fig. 9 is a section on the line 9 9, Fig. 5; Figs. 10 and 11 are, respectively,plan and side elevational views of a preferred ,form of pusher element illustrating an element of the invention;

Fig. 12 is a section on the line 12,-12, Fig. 11, 10 and Fig. 13 is a fragmentaryV sectional view illustrating the relationbetween the tuyres and retorts.

With reference to the drawings,` a stoker em.- bodying the present invention may comprise a 7,5 plurality of transversely spaced inclined beams 1v preferably of steel which dene and constitute portions of the side Walls of alternating retort and tuyre sections. The lower ends of these beams are individually supported upon a .girder $0 2 through the medium of a roller or rollers 3 whereby the lower ends of the beams 1 are kfreely self-adjustable under the'` effects of longitudinal expansion and contraction. The upper ends of the beams 1 are supported upon pivot pins 4 85 carried in brackets 5 at the top of columns (i at f the front end of the stoker structure. In addition to the pivotal connection, each of the beams 1 is secured to the brackets by means of bolts 7, and the holes in the beams 1 through which these 90 bolts extendare made suiciently larger in diameter than the bolts themselves to afford the said beams limited free movement upon the pivot pins 4. This free pivotal mounting at the tops of the beams in conjunction with the aforedescribed roller support at the lower ends affords a completely free adjustability in the beams for expansion and contraction and relieves the beams of all stresses and strains arising from that cause.

As shown in Fig. 2, those of the beams 1 which 100 are secured to the opposite faces of adjoining bracket 5 are joined together at predetermined spaced points throughout their lengths by means of plates 8, these plates being substantially horl- Zontally arranged and defining spaces inV which operate pushers 9, these pushers being reciprocated in well known manner through the medium of rods 11, see Fig. l. The plates 8 accordingly form a portion of the bottom Wall of the retort structure, and in addition` to uniting the side walls of the individual retorts also form supports and spacers for the pushers 9. Between the brackets 5 at the upper end of each of the retorts is secured an inclined dead plate 12 onto which fuel is fed by the stoker'main rams 10, see Fig. 3, in the usual manner. The lower end of the dead plate 12 terminates at a point contiguous to the upper face of the uppermost of the pushers 9. Y f

Mounted at the upper edge of each cf the beams 1 is a series of side plates 13, these plates forming the upper Walls of the retorts and also constituting supports for the tuyres 14 which bridge the spaces between the retorts in the usual manner. Secured to the beams 1 below the side plates 13 are facing plates 15, which plates with the side plates 13 and portions of the dead plates 8 form the plane side-wall surfaces of the retorts and side bearings for the pushers 9. Secured in part to the beams 1 and in part to the brackets 5 are top end plates 16 which with plates 17 and `18 secured to the faces of the brackets terminate the upper side walls of the retorts. These plates 16, 17 and 18 also function to protect the brackets 5 from the abrasive effects of fuel fed to the retorts over the dead plates 12.

The dead plates 8, which may vary slightly in form in accordance with their positions between the beams 1, each comprises essentially an upper rear surface 21 which forms a bearing surface for they pushers 9 and which is bounded at the sides by upwardly extending flanges T22; and a forward inclined upper surface 23, this surface terminating in a short nose surface 24 ofvstill steeper inclination as illustrated. The dead plates 8 .act as bearings for several columns of fuel in the retorts and prevent recession of the fuel during the return stroke of the pushers 9. The nose surface 24 is adapted for reception of a resilient scraper blade 25, which as illustrated may be secured to the dead plate by means of bolts, this resilient scraper blade in each instance bearing resiliently upon the upper surface of the underlying pusher to thereby form an effective seal against siftings tending to pass rearwardly between the upper surfaces of the pushers and the overlying dead plates into the space below the retorts, which in the stoker structure constitutes the wind-box lfrom which air is fed to the tuyres. The scraperl blades '25 extend completely across the individual retorts between the side plates forming the retort Wall surfaces.

Also as best illustrated in Figs. 4 to k9, inclu-l sive, the side fianges 22 ofthe deadplates 8 terminate at the forward ends in inclined surfaces 26, which inclined surfaces in assembly lie contiguous to the inclined lower edges of the side plates 13 whereby the flanges 22 in effect are made to form a part of the effective side wall surface of the retort. Also in assembly, the lower edges of the side plates l5 abut the upper edges of the flanges 22. Each of the dead plates 8 also comprises a depending ange 27 which in assembly abuts the sides of the beams l and isprovidcd with slotted holes 28 through which pass the bolts 29 by means of which the dead plates are secured to the beams 1.

As illustrated in Fig. 1, it is preferred'to pro-V surface with a series of teeth 32 which present sharp edges to the underlying surface of the individual dead plates and tend also to prevent siftings from passing rearwardly between the dead plates and the pushers, see Figs. 10 and l1. Also as shown in these figures, I may provide each of the pushers with side scraper blades 83 which resiliently engage the side Wall surfaces of the retort for preventing siftings between the pushers and these side walls. As best shown in Fig. 12, the side walls of the pushers may be provided with rearwardly and upwardly inclined recesses 34 which may extend from the tcp surface of the pusher to the bottom, each recess including an inner surface 35 formed at an acute angle to the normal side surface of the pusher, against which inclined surface the blades 33 may be secured by means for example of bolts 36, the blades projecting forwardly and outwardly beyond the plane of the normal side surface of the pusher. The blade 33 may be made ofV resilient spring steel which in practice bears resiliently against the side of the retort and effectively excludes the siftings, as set forth. Will thus be noted that provision is made for preventing passage of siftings on all four sides of each individual pusher element. Also, by reason of the joining together of the side walls of the retort sections by the dead plates 8 the expansion in the individual retorts is controlled to an extent preventing the development of undue clearances between the pushers and the walls of the retort whereby the aforedescribed sealing means are rendered continuously effective and their efficiency maintained. The sealing means in conjunction with the Stoker structure thereby affords an extremely 'effective seal between the pushers and the retort walls and limits the siftings to a negligible quantity.

It will further be noted that by reason of the aforedescribed method of mounting the main beams 1, the stoker grate vstructure as a whole is afforded a maximum flexibility permitting Vfree adjustment of the parts under expansion and contraction due to varying temperatures. The transverse expansion of the individual retorts is absorbed entirely in the tuyre sections, there being sufficient clearance provided between the tuyre elements and the supporting side plate'13, Y.

see Fig. 13, to permit a maximum expansion without binding.l Thus the expansion of one retort is not passed onto and does not affect the adjacent retorts whereby accumulative expansion in the structure as a vwhole is entirely avoided. This permits relatively small clearances between the side Walls of the furnace and the Stoker structure and materially aids in the production of a satisfactory seal between the sides of the stoker and the walls of the furnace.

During the operation of the Stoker a layer of incandescent fuel completely covers the fuel bed. Beneath this layer is a layer of partially consumed fuel resting upona layer of fuel which has reached the coking stage. These Various layers of fuel are supported upon green fuel which completely fills the retorts. During the process of combustion fuels such as coal expand and become somewhat sticky, thus causing the various particles thereof to adhere to each other. This action is even more pronounced when the fuel is compressed into a compact mass by the main rams. The fuel in this state is supported at spaced points upon the tuyre rows and bridges the top of the retorts forming an arch, and thus the green fuel in the retorts may be moved relative thereto.

It will further be noted that the fixed dead plates 8 constitute a part of the effective bottom wall of the individual retorts. This has been found to be a decided advantage in the maintenance of a desirably solid and compact fuelbed, since the dead plates establish points of fixed support throughout the fuel-bed, at which points the fuel is not subject to the disturbing action of the pushers. In the prior stokers, where the bottoms of the retorts are formed entirely by the movable pushers, the fuel is kept in continuous agitation, which has been found to interfere with efficient combustion. With the present construction, the efficiency of the Stoker is relatively high.

It will be understood that there may be considerable modification aS to form without departure from the invention, as defined in the appended claims.

I claim:

1. In a stoker, a pair of spaced inclined beams, facing means provided on said beams, said beams and facing means defining the sides of a retort, a series of spaced substantially horizontal dead plates extending between and joining said beams, and pushers mounted for reciprocation between said dead plates and with said plates forming the bottom of the retort. Y

2. In a Stoker, a retort comprising side walls, fuel-supporting and feeding pushers mounted for reciprocation between said walls, flat spring elements operative between the sides of the pushers and the walls of the retort to prevent siftings therebetween, means for joining the walls of said retort to prevent separation of said walls tending to reduce the efciency of said sealing means, and additional sealing means between the pushers and said means for joining the walls of the retort for preventing the passage of siftings therebetween.

3. In a Stoker, a retort structure comprising side walls, fuel-supporting and feeding pushers operative between said walls, dead plates secured to said Walls and separating said pushers, and means for sealing the joints between the pushers and said walls and dead plates whereby the sifting of fuel between said joints is substantially prevented.

4. In a Stoker, a retort structure comprising side walls, a series of fuel-supporting and feeding pushers operative between said side walls in substantially horizontal planes, and dead plates secured to and extending between Said side walls and separating said pushers, said dead plates constituting a portion of the fuel-Supporting bottom wall of the retort.

5. In a stoker, a retort structure comprising side wall members, dead plates secured between said members in spaced relation, each of said dead plates having at the sides upwardly projecting flanges lying adjacent vto said wall members, facing plates secured to said wall members and forming with said flanges the effective side surfaces of the retort, and pushers mounted for reciprocation on said dead plates and between said flanges.

6. In a stoker, a relatively fixed retort'structure comprising inclinedV transversely spaced beams and facing means provided on said beams, said beamsl and facing means forming the sides of said retort, spaced brackets provided at the upper end of the stoker, means for pivotally supporting the upper ends of said beams on said brackets to ,permit oscillatory movement in a vertical direction, anti-friction bearings for the bottoms of said beams, said pivotal support and bearings affording free adjustment of said beams due to longitudinal expansion and contraction, and a series of pushers and dead plates forming the bottom of said retort.

7. In a Stoker, a retort structure comprising transversely spaced inclined beams and facing means provided on said beams, said beams and facing means forming the side walls of said retort, spaced brackes forming a support for the upper ends of said beams, spaced dead plates extending between adjacent beams constituting the opposite walls of said retort fuel-supporting and feeding pushers operative between said retort walls and said dead plates, means for feeding fuel into said retort between said brackets, and facing plates secured to said brackets and forming side abutments for the said fuel passing to the retort.

8. In a multiple retortl underfeed stoker, the combination with a primary ram for feeding and tightly packing the fuel into the retorts, of a series of spaced dead plates mounted in the bottom of each retort, a series of substantially horizontal pushers mounted for reciprocation between said dead plates, said pushers being provided with a substantially vertically disposed pushing surface for advancing the fuel along said retorts, and said dead plates forming fixed supports for the fuel in the retors, and prevent recession of the fuel advanced by said pushers.

9. In an underfeed Stoker, the combination with a plurality of fuel retorts, a plurality of primary rams for feeding and tightly packing the fuel into said retorts, of a series of spaced dead plates mounted in the bottom of each retort, a series of pushers mounted for reciprocation between said dead plates, tuyres spanning the space between adjacent retorts, said tuyres constituting a support for the fuel bridging the top of said retorts, said pushers being provided with a substantially vertical fuel advancing surface, and said dead plates forming a series of fixed supports for the fuel in said-retorts, and prevent recession of said fuel during the return movement of said pushers.

10. In a long underfeedstoker, the combination with a series of alternately disposed retorts and tuyre rows, said relortshaving side and bottom walls, said bottom walls comprising a series of spaced dead plates, and fuel feeding pushers mounted for reciprocation therebetween, said pushers and dead plates being mounted in such a manner that the front ends of the retorts are comparatively deep while the retorts become progressively shallower from front to rear of the Stoker, a primary ram for each retort for feeding and tightly packing the fuel therein, said tuyre rows forming a support for the fuel bridging the top of said retorts, and said dead plates forming a series of fixed supports for the fuel in said retorts preventing a recession of the fuel during the return movement of said rams.

HERBERT E. PRESTON. 

